Yersinia pseudotuberculosis bacteraemia with splenic abscesses: a case report

Introduction. Yersinia pseudotuberculosis has been known to cause a variety of clinical manifestations ranging from mild enteric illness to bacteraemia with septic shock and extraintestinal abscesses. Patients with liver disease and iron overload are at risk of more severe disease manifestations. Case Report. A middle-aged male with chronic alcohol use disorder presented with confusion and jaundice, with ascites and asterixis noted on examination. His blood work was remarkable for neutrophilic leukocytosis, elevated liver enzymes and lactate. An abdominal computed tomography scan revealed splenic microabscesses and a cirrhotic liver. Yersinia pseudotuberculosis was recovered from his blood cultures and he was treated with ceftriaxone following susceptibility results. Conclusion. Y. pseudotuberculosis should be considered in the differential diagnosis of splenic or other extraintestinal microabscesses particularly in patients with chronic liver disease.


BACKGROUND
Yersinia pseudotuberculosis is a Gram-negative bacillus from the family Yersiniacae.Similar to another member of the family, Yersinia enterocolitica, Y. pseudotuberculosis most commonly presents with enteric illness [1].
The sources of infection with Y. pseudotuberculosis include contaminated food such as dairy products and vegetables or contaminated water [2].Several animals including birds, dogs, rodents, rabbits, deer and farm animals can serve as reservoirs [1,2].Direct contact with these animals has also been described as a mode of acquisition [1,2].Community outbreaks secondary to consumption of contaminated lettuce, carrots and water have been reported in Finland, Japan, Russia and Canada [3,4].
Although it often presents as mild gastroenteritis, several other clinical manifestations have been reported with Y. pseudotuberculosis [1].Pseudoappendicitis with mesenteric lymphadenitis is a well-described phenomenon and many patients in the 20th century underwent appendectomies due to erroneous diagnosis after presenting with right lower quadrant abdominal pain [5].Bacteraemia is rare and when it occurs it has been associated with abscesses in the spleen, liver, kidneys and lung with a granulomatous appearance that mimics tuberculosis [5,6].Although it is commonly a self-limiting illness in immunocompetent patients, septicaemia with Y. pseudotuberculosis infection is thought to carry a fatality rate that exceeds 75 % without use of antibiotics [2].
Here we present a case of Y. pseudotuberculosis bacteraemia with splenic abscesses in a patient with previously undiagnosed liver cirrhosis.

Clinical presentation
A middle-aged male patient with chronic alcohol use disorder and a recent trip to Mexico presented with a 2 week history of progressive confusion and jaundice.
He complained of abdominal pain in the previous week and increasing abdominal girth for the prior 2 weeks.He did not have any diarrhoea or frank abdominal pain, fevers or chills.He denied any respiratory, cardiac or urinary symptoms.
The patient did not have any immune compromising conditions and he was not taking any home medications.However, he had chronic alcohol use disorder with 25-50 oz (740-1479ml) of vodka per day for over 10 years.He also had a unilateral eye prosthesis following globe rupture from glass trauma 20 years previously.
He recently returned from a 2 week trip to Mexico where he denied consuming any unpasteurized milk, raw meat or raw vegetables.The patient recalled having barbecued pork meat that he thought was well cooked.

Physical examination
The patient appeared confused but not in any distress in the initial assessment.His blood pressure was 104/72 mmHg, pulse 124 beats per minute, temperature 36.5 °C and respiration rate of 18 breaths per minute with oxygen saturation of 93 % on room air.His examination was notable for mild asterixis, jaundice as well as soft, non-tender abdomen with mild ascites.

Radiographic investigations
A computed tomography (CT) scan of the abdomen revealed splenomegaly with innumerable hypodense lesions in the spleen consistent with microabscesses, nodular liver and moderate ascites (Figs 1 and 2).
Fig. 1.CT scan of the abdomen with contrast, coronal view.Numerous hypoattenuating small nodules are seen throughout the spleen (red arrow).These imaging features are non-specific, but are compatible with microabscesses.The liver is nodular, and the spleen is moderately enlarged.Perihepatic and perisplenic ascites (yellow arrows) are present, in keeping with underlying cirrhosis.There are no obvious hepatic masses or abscesses.
Fig. 2. CT scan of the abdomen with contrast, axial view.Numerous hypoattenuating small nodules are seen throughout the spleen (red arrow).These imaging features are non-specific, but the radiographic appearance is compatible with microabscesses.The liver is nodular, and the spleen is moderately enlarged.Perihepatic and perisplenic ascites (yellow arrows) are present, in keeping with underlying cirrhosis.There are no obvious hepatic masses or abscesses.

Microbiology investigations
Blood cultures grew Gram-negative coccobacilli in all four bottles.Gram staining showed short Gram-negative bacilli (Fig. 3).The bacterium was identified as Y. pseudotuberculosis by Vitek MS (bioMérieux) matrix-assisted laser-desorption/ionization time-of-flight (MALDI-TOF) MS, a fully validated method for routine bacterial identification in our clinical laboratory [7].Mass spectra profiles were analysed using the commercial Vitek MS database (MS-ID version v.3.2) and a high confidence score of 100 % was obtained.Antibiotic susceptibility testing (AST) was performed using the Kirby-Bauer disc diffusion method.Y. pseudotuberculosis was susceptible to ampicillin, cefazolin, ceftriaxone, piperacillin-tazobactam, ciprofloxacin, trimethoprim-sulfamethoxazole, gentamicin and tobramycin.Ciprofloxacin susceptibility was confirmed by the gradient diffusion method (i.e.Etest; bioMérieux) with MIC of 0.032 µg ml −1 .AST results were interpreted as per the Clinical and Laboratory Standards Institute (CLSI) guidelines for Enterobacterales [8].

Treatment and follow-up
On admission, the patient was empirically started on intravenous piperacillin-tazobactam which cleared his bacteraemia within 48 h.Six days after admission, he underwent a diagnostic and therapeutic paracentesis.His peritoneal fluid analysis was consistent with bacterial peritonitis with white blood cell count of 1176×10 6 l -1 and 50 % neutrophils.However, as this was collected after 6 days of antibiotics, peritoneal fluid Gram stain showed 2+ mononuclear cells with no organisms seen and there was no growth on culture.
During his hospital stay, the patient was also found to have bilateral redness of his eyes with associated occasional discharge.He was evaluated by ophthalmology on day 9 of admission.At the time of his ophthalmology examination, however, his symptoms had resolved with no further eye redness or discharge.Both his native eye and contralateral eye socket with an eviscerated globe appeared healthy on anterior and posterior segment examination by ophthalmology with no findings of conjunctivitis or endophthalmitis.
The patient's confusion, thought to be due to hepatic encephalopathy, resolved with lactulose treatment.Once susceptibilities became available, he was switched to intravenous ceftriaxone to complete a total of 14 days of parenteral antibiotic treatment.His liver enzymes also improved markedly a week after his admission and the patient was subsequently discharged home.

DISCUSSION
Y. pseudotuberculosis is a non-lactose-fermenting Gram-negative bacillus with characteristic bipolar staining.It is a urease-positive but indole-and oxidase-negative organism that is motile at room temperature [9].In addition to MALDI-TOF MS, it can be identified by automated biochemical methods such as Vitek2 ID (bioMérieux).
Since its first isolation in 1883, Y. pseudotuberculosis has been reported across the globe with a range of clinical manifestations [10].A Y. pseudotuberculosis outbreak associated with homogenized milk from a milk plant occurred in Canada in 1998 [11].This outbreak reported 74 laboratory-confirmed cases in the province of British Columbia, with isolation of Y. pseudotuberculosis from stool, blood or mesenteric nodes [11].Currently available reports of Y. pseudotuberculosis infections describe great variability in the extent of disease severity.Severe manifestations include bacteraemia with or without septic shock, hepatic or splenic abscesses, and rarely facet joint infections and septic arthritis [2,10].
Beyond acute infectious presentations of bacteraemia and extraintestinal abscesses such as splenic abscesses, Y. pseudotuberculosis is also known for its immunological complications.Immunological complications of Y. pseudotuberculosis infection include erythema nodosum, glomerulonephritis, reactive arthritis, isolated conjunctivitis, iritis and onset of Kawasaki disease [1].In our patient, his new-onset bilateral redness of his eyes raised a concern for an immunological complication such as conjunctivitis.However, these remain unproven given the complete resolution of these symptoms at the time of his ophthalmological assessment.Another complication, Far East scarlet like fever (FESLF), is a severe systemic inflammatory manifestation secondary to hypervirulent strains of Y. pseudotuberculosis first described in Russia in 1959 [5,12].FESLF presents with fever, desquamating rash, variable neurological and gastroenterological symptoms, and rarely cardiovascular symptoms such as arrhythmias [5].
Several patient risk factors associated with severe and systemic Y. pseudotuberculosis infections have been described.These include iron overload disorders such as haemochromatosis, cirrhosis, thalassaemia, and haemolytic anemias in addition to immunosuppression [2,13].Iron overload disorders create a favourable environment for Y. pseudotuberculosis because of its ability to bind iron through secondary metabolites called siderophores [13].Iron is essential for bacterial growth and is often sequestered in live mammalian hosts becoming inaccessible to many bacteria [14,15].Similar to other members of the family Yersiniace, Y. pseudotuberculosis scavenges iron by using siderophores such as yersiniabctin (Ybt) with high affinity for ferric (Fe 3+ ) ions present in mammalian hosts [13].As a result of its efficient iron scavenging systems, Y. pseudotuberculosis can effectively grow and cause severe illnesses such as bacteraemia and extraintestinal abscesses, with greater mortality in patients with iron overload disorders such as liver disease and haemochromatosis [16].The ability of Y. pseudotuberculosis to sense iron availability and oxidative stress has been proposed as the rationale for more extraintestinal dissemination in hosts with iron overload as Y. pseudotuberculosis would be more likely to cross the intestinal barrier into deeper organs such as the liver and spleen [17].
In our patient, his presenting symptoms of jaundice, confusion and abdominal girth were secondary to decompensated liver cirrhosis rather than Y. pseudotuberculosis bacteraemia.However, his liver cirrhosis and severe alcohol use disorder, which resulted in a state of iron overload, probably led to a more severe and invasive presentation of Y. pseudotuberculosis infection with bacteraemia and splenic abscesses.Both severe alcohol use and liver cirrhosis have been shown to affect iron metabolism by increasing iron stores at the liver parenchyma and reticuloendothelial system [18,19].Notably, our patient had an elevated transferrin saturation of 0.64 suggestive of increased iron stores although his ferritin was not assessed (Table 1).
Interestingly, our patient presented with bacteraemia associated with splenic microabscess without any hepatic abscesses.Prior to identification of Y. pseudotuberculosis in his blood cultures, the radiographic differential diagnosis for his splenic microabscesses included fungal infection, bacterial infection with atypical bacteria such as Salmonella spp.and Mycobacterium spp., granulomatous disease with sarcoidosis or lymphoma.
Hepatosplenic dissemination of Y. pseudotuberculosis was previously thought to result from the ability of this species to be translocated by specialized intestinal epithelial cells into lymphoid Peyer's patches of the ileum [20].Y. pseudotuberculosis possesses a protein on its outer membrane, invasin, that can bind to intestinal epithelial cells, and this was thought to facilitate the uptake and dissemination of Y. pseudotuberculosis into Peyer's patches and subsequently into mesenteric lymph nodes that drain into the bloodstream [21,22].Although this hypothesis had been widely accepted, recent studies with mice have demonstrated that extraintestinal spread of Y. pseudotuberculosis is complex and involves alternative routes such as movement into the portal vein system from the intestinal epithelium and reaching the liver and spleen through the pathway of the portal vein rather than by lymphatic drainage [20].Furthermore, in Peyer's patch-deficient mice, it was shown that dissemination of Y. pseudotuberculosis into the spleen, liver and mesenteric lymph nodes was not reduced, calling into question the role of Peyer's patches in hepatosplenic dissemination [22].
Since the first reported human case of Y. pseudotuberculosis bacteraemia in 1911, there have been seven reports of splenic abscesses [10].Four of these were isolated splenic abscesses while the others occurred in conjunction with hepatic abscesses and in one case along with renal abscesses [7,[23][24][25][26].It is worth noting that four out of the seven cases were fatal [10].All of the four fatal cases were described before 1943, prior to mass production of penicillin for clinical application, and the patients in these cases did not receive any antimicrobial therapy [10,27].
In previously reported cases of bacteraemia due to Y. pseudotuberculosis, treatments with penicillin, first-and third-generation cephalosporins, fluoroquinolones and carbapenems have been used with successful clinical outcomes [2].The optimal antimicrobial choice, however, has not been formally established yet.

Please rate the quality of the presentation and structure of the manuscript Satisfactory
To what extent are the conclusions supported by the data?Partially support

Response to Reviewers' comments:
Please rate the quality of the presentation and structure of the manuscript Reference 20-23 are case reports of Y. pseudotuberculosisin specific patients such as kidney transplant, hemochromatosis and diabetic patients.As this organism is not commonly encountered, case reports of its manifestation in different patient populations such as immunocompromised patients have occurred sporadically throughout the decades.We believe it is important to include the various manifestations of this infection across different patient populations as reported in prior literature so that clinicians are aware of the disease spectrum.We have edited the presentation section as per above feedback.Is there any other simple method for the identification of Yersinia rather than using matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry?
We do not have photographs of colony morphology as our photographs during work-up were only of gram stain which we have provided in the manuscript.We have described colony morphology.
We have added automated biochemical methods such as Vitek2 as other simple methods of identifying Yersinia beyond MALDI-TOF in lines 129-130.
Please rate the quality of the presentation and structure of the manuscript We have added bacteremia as one of the keywords.
4. Graphical abstract will illustrate the case study details more easily.It should elaborate case timeline and past medical history.
Given that our manuscript is a case report of a single case patient without laboratory value trends with relatively straightforward clinical timeline, we have decided that a text abstract captures the case presentation well similar to previously published case reports on the journal and therefore we have not pursued a graphical abstract.

Write methodology as a separate section and use subheadings to demonstrate each step.
As this is a clinical case report of a single patient without any diagnostic or treatment experiments, we have not included a "Methodology" section similar to Case Reports previously published on Access Microbiology.
Laboratory and radiographic investigations including microbiology were obtained as part of standard clinical practice with no and no specialized research methodology was employed.
We have outlined methods used in obtaining microbiological investigations in detail in lines 104-119.
6. Use subheading in the results section.
We have included subheadings in the investigation section.
7. Yersinia should be written only when mentioned for the first time in the manuscript then will bw written as Y. .We have revised the paper to reflect this feedback.

The whole paper needs a careful English grammar and spelling revision:
We have revised the paper in its entirety to reflect this feedback.9. References should be modified according to journal instructions: bold authors names, only first initial should be writtenand journal name should be italic.
We have bolded authors' names and italicized journal names.Please note that the journal states that references should be cited in Vancouver style and prior publications have included references with some authors' names with first initial as well as first and middle initial together when provided by original articles.
Please see below a case report published in the journal for an example.https://www.microbiologyresearch. org/ content/ journal/ acmi/ 10. 1099/ acmi.0. 000173 10.Patient consent and ethical approval code should be provided.
Given that this is an anonymous clinical case report of a single patient without any diagnostic or treatment experiments, we have obtained verbal patient consent and have stated this in text.
As we have not included any patient identifier's in this clinical case report with no intervention, based on the journal's requirement for such clinical case reports, an ethical approval code was not pursued.

In Results section: antibiogram results should be clearly tabulated for both disc diffusion technique and E-test.
We have included this information in lines 103-108 with an addition of E-test results for ciprofloxacin AST confirmation.
12. In Discussion section: antibiogram susceptibility results should be compared with previously published articles.
This pathogen is often relatively susceptible to commonly used antibiotics and the isolate in our case was reflective of that with no particular challenge in regards to resistance to common antibiotics.Furthermore, in balancing measure of feedback given below (20), in shortening the discussion, we have decided to not include AST comparisons with prior literature as we believe the value added by such discussion is not paramount for this case report.13.Was this patient suffering from SARS-CoV-2?.
The patient was not suffering form SARS-CoV-2.He had no respiratory symptoms and had a negative SARS-CoV-2 PCR test from nasopharyngeal swab that was done on his admission.
14. Kindly add table of abbreviations (e.g.lines 95 and 96) and mention the normal ranges.
We have added a table of laboratory abbreviations along with normal reference ranges.15.Regarding bilirubin, direct, indirect and total values should be provided to determine type of jaundice.
We have provided direct bilirubin and total bilirubin values.16.Line 106, add year of CLSI edition used.
We have used 2022 CLSI and added this in the text.17.Adding antibiogram in material and methods section is recommended.
We have included the antibiogram in the results section with Kirby Bauer disk diffusion and E test results in lines 103-108.18. Antibiogram results for the isolate should be mentioned in details.
Please see above comments regarding antibiogram.19.Lines 117-122: this paragraph is not obvious at all and should be rewritten.
We have rewritten this paragraph.

Discussion is too long
We have revised discussion in light of this feedback with balance to other feedback to include additional information on discussion.

Line 170: bacterial names should be italics
We have italicized all bacteria names.We used Vitek MS to identify this organism and added detailed information around MALDI in lines 105-112.We have fully validated the FDA approved Vitek MS (bioMérieux) MALDI-ToF system for routine bacterial identification in our clinical laboratory.Mass spectra profiles were analyzed using the commercial Vitek MS database (MS-ID version v.3.2).At this time the mass spectra is no longer available to us and thus we cannot provide documented figure.
In addition to Yersinia pseudotuberculosis, additional species of Yersiniaincluded in our MALDI database are: Yersinia enterocolitica, Yersinia frederiksenii, Yersinia intermedia, Yersinia kristenseni.

conclusion must be rewritten and supported by data
We have rewritten our conclusion to reflect the clinical course of the patient and investigations.

Lines 157-160: explain the relation between iron and extraintestinal abscesses
We have explained this in lines 161-164.

Regarding clinical manifestations of patient:
a. Was the patient feverish as splenic abscess is usually accompanied by severe fever?
As we have described in "Clinical Presentation" sections in line 72 and 83, patient did not have any fevers at home or on arrival to hospital.
We have also provided his temperature measurement in "Physical Examination" section line 87.. to underscore that patient did not have fever.
b. Was prokinetic drugs administered?Prokinetic drugs were not administered.

c. Procalcitonin test performed?
Procalcitonin was not performed.Procalcitonin is not a routine test in clinical practice at our institution / patient's country of residence.It is often pursued only when microbiologic investigations such as blood cultures return negative and patient have persistent fevers without an obvious infectious foci on imaging and microbiological investigations.Reviewer 4 Comments to Author: Zewude et al provide a case report for a pa8ent with bacteremia purported to be Yersinia pseudotuberculosis, hepa8c encephalopathy, and splenic abscesses.While this is an interes8ng and relevant case report if indeed the splenic abscesses were caused by Yersinia, the data showing that the cultured bacteria was indeed Yersinia pseudotuberculosis was not provided.In addi8on, the sequence of events and whether all the symptoms were caused by the Yersinia pseudotuberculos infec8on is not made clear.
We have provided detailed data regarding MALDI-TOF identification of Y. pseudotuberculosis from blood cultures in lines 97-102.
We have also provided outline of patient's presenting symptoms in "Clinical Presentation" section, and resolution of some of these symptoms following 9-days of antibiotics for Y. pseudotuberculosis in the "Treatment and Follow Up" section line 134-138.The patient's confusion and increasing abdominal girth were the results of his decompensated cirrhosis rather than Y. pseudotuberculosisinfection.However, his undiagnosed underlying liver cirrhosis which causes iron overload, was what had predisposed patient to have more invasive and severe disease with Y. pseudotuberculosiswith bacteremia and splenic abscesses.
We have included a section in the discussion lines 181-188-to outline the patient's illness course and the connections of his symptoms with cirrhosis and Y. pseudotuberculosis more clearly.

Major comments:
1) This reviewer is not familiar with enteropathogenic Yersinia being spread by direct contact with animals (lines 53-54).It is known to be spread by ea8ng undercooked pork, but this is dis8nct from "direct contact".Furthermore, references #1 and 2, which are cited in this sentence, do not state that transmission of enteropathogenic Yersinia can occur by direct contact.Rather, reference #1 discusses some mammals as reservoirs.
Reference #2 states that transmission can occur by direct contact with infected animals.Please see below with the following direct quote from Hashimoto et al.
"Transmission to humans is uncommon and occurs through the ingestion of contaminated food, water or milk, or direct contact with an infected animal, such as rodents, rabbits, deer, farm animals, and birds" 2) The MALDI-TOF data showing that the bacteria from the blood was iden8fied as Yersinia pseudotuberculosis is not shown.This is the most cri8cal piece of data for this manuscript and must be provided and properly annotated.In addi8on, if possible, ideally sequencing of 16s rRNA and other genes such as invasin and YopJ should be shown as confirma8on.
We have added MALDI-TOF data in lines 105-112.We do not have 16s rRNA sequencing data as this is not routinely done for positive blood culture isolates in our institution's clinical practice for positive blood culture isolates.
3) Line 113: If paracentesis showed no bacterial growth then why did peritoneal fluid show bacterial peritoni8s.Was the paracentesis sampled from the peritoneal cavity or another 8ssue?Was paracentesis and peritoneal fluid sampling done on the same day?Please clarify this sec8on.Did this peritoneal infec8on get cleared by the second course of an8bio8cs?
As we have outlined in lines 123-124, his paracentesis was done 6-days after IV piperacillin-tazobactam therapy.Often in cases of specimens collected days after antibiotics, particularly few days after antibiotics, the diagnostic yield of culture is low as the antibiotics sterilize the sample and therefore bacteria are not usually isolated in such specimen.However, the biochemical analysis of such specimens i.e. cell count with differentials of white blood cells, serve as useful marker of infection as they often persist as abnormal even after days of antibiotics.Therefore, it is routine clinical practice to treat such cases whereith specimens are collected after days of antibiotics as infection if their showing biochemical analysis is consistent with infection but negative cultures as infection cultures return as negative.
Paracentesis is the routine clinical procedure for peritoneal fluid collection.
4) It is not clear whether the pa8ent's confusion and elevated liver enzymes resolved.
We have described that both his confusion resolved in lines 122 and his liver enzymes improved in line 125.5) Lines 172-182: Barnes et al (reference #17) showed that Yersinia pseudotuberculosis in mice need not transit through the Peyer's patches to colonize the spleen and liver in mice.In fact, Yersinia found in the Peyer's patches seem not to have the capacity to effec8vely colonize the spleen and liver as shown by Barnes et al.Therefore, the first sentence of this paragraph is inaccurate.Furthermore, because of this, it is not clear whether this paragraph is relevant.
We have revised this paragraph to capture the evolution in thought processes around the role of Peyer's patches in Y. pseudotuberculosisdissemination.

6) Fig 3 needs a scale bar.
Given that we have provided magnification power and that this is a gram stain rather than colonic morphology, we believe a scale bar is not indicated for this figure.
Perhaps what is meant is "piperacillin-tazobactam to treat an unknown culprit pathogen"?Edited as per comment above 2) Line 50: There is more than two species of Yersinia in the family Yersiniacae.Therefore, "similar to the other member of the family" should be changed to "similar to another member of the family".
Edited as per comment above 4) Lines 75-67: Rather than "last week" or "last 2-weeks", it should say "the previous week" or "the previous two weeks".The sentence should also be changed to past tense rather than presence perfect tense: for example, "has had" is incorrect.
Edited as per comment above 5) Line 74: The fall from fishing is more appropriate to discuss in lines 82-85 when the trip to Central America is discussed.
Edited as per comment above 6) Line 133: The word "nodes" is missing.
We had already included the word "nodes" in this sentence but we have revised sentence for better clarity.7) Line 141: Did the authors mean "iri8s" rather than "irits"?
We referred to "iritis" i.e. inflammation of the iris as this is one of the known immunological complications of Y. pseudotuberculosisinfection 8) Is conjunc8vi8s an "immunological" complica8on?Reference #1 lists it simply as a "complica8on".
Conjunctivitis is an immunological complication.Although reference #1 does not explicitly state it as immunological complication as discussed throughout text and other included reference it occurs following acute infection with Y. pseudotuberculosis.
Here is a paper discussing ophthalmologic complications -uveitis or conjunctivitis occurring following Y. pseudotuberculosis infection.We have also included direct quote from this paper regarding the immunological nature of this complication for the interest of reviewer.Saari, K.M., Mäki, M., Päivönsalo, T. et al.Acute anterior uveitis and conjunctivitis following yersinia infection in children.Int Ophthalmol 9, 237-241 (1986).https:// doi.org/ 10. 1007/ BF00137536 -"In this study four patients developed nongranulomatous acute anterior uveitis or conjunctivitis from one to three weeks after onset of Yersinia infection.In all patients of this study raised antibody titres indicated the presence of a recent yersinia infection".9) Yersinia pseudotuberculosis was first described in 1883 but the first reported case was in 1911?Please clarify.
The bacteria was first isolated from guinea pigs and human feces in Argentina in 1883 but the first described human case of bacteremia was reported in 1911.

Date report received: 09 June 2023 Recommendation: Major Revision
Comments: Zewude et al provide a case report for a pa8ent with bacteremia purported to be Yersinia pseudotuberculosis, hepa8c encephalopathy, and splenic abscesses.While this is an interes8ng and relevant case report if indeed the splenic abscesses were caused by Yersinia, the data showing that the cultured bacteria was indeed Yersinia pseudotuberculosis was not provided.In addi8on, the sequence of events and whether all the symptoms were caused by the Yersinia pseudotuberculos infec8on is not made clear.Major comments: 1) This reviewer is not familiar with enteropathogenic Yersinia being spread by direct contact with animals (lines 53-54).It is known to be spread by ea8ng undercooked pork, but this is dis8nct from "direct contact".Furthermore, references #1 and 2, which are cited in this sentence, do not state that transmission of enteropathogenic Yersinia can occur by direct contact.Rather, reference #1 discusses some mammals as reservoirs.2) The MALDI-TOF data showing that the bacteria from the blood was iden8fied as Yersinia pseudotuberculosis is not shown.This is the most cri8cal piece of data for this manuscript and must be provided and properly annotated.In addi8on, if possible, ideally sequencing of 16s rRNA and other genes such as invasin and YopJ should be shown as confirma8on.3) Line 113: If paracentesis showed no bacterial growth then why did peritoneal fluid show bacterial peritoni8s.Was the paracentesis sampled from the peritoneal cavity or another 8ssue?Was paracentesis and peritoneal fluid sampling done on the same day?Please clarify this sec8on.Did this peritoneal infec8on get cleared by the second course of an8bio8cs?4) It is not clear whether the pa8ent's confusion and elevated liver enzymes resolved.5) Lines 172-182: Barnes et al (reference #17) showed that Yersinia pseudotuberculosis in mice need not transit through the Peyer's patches to colonize the spleen and liver in mice.In fact, Yersinia found in the Peyer's patches seem not to have the capacity to effec8vely colonize the spleen and liver as shown by Barnes et al.Therefore, the first sentence of this paragraph is inaccurate.Furthermore, because of this, it is not clear whether this paragraph is relevant.6) Fig 3 needs a scale bar.Minor comments: 1) Line 36: "piperacillintazobactam with unknown culprit pathogen" doesn't make sense.Perhaps what is meant is "piperacillin-tazobactam to treat an unknown culprit pathogen"?2) Line 50: There is more than two species of Yersinia in the family Yersiniacae.Therefore, "similar to the other member of the family" should be changed to "similar to another member of the family".3) Lines 73-76 should say "two weeks" rather than "2-weeks".4) Lines 75-67: Rather than "last week" or "last 2-weeks", it should say "the previous week" or "the previous two weeks".The sentence should also be changed to past tense rather than presence perfect tense: for example, "has had" is incorrect.5) Line 74: The fall from fishing is more appropriate to discuss in lines 82-85 when the trip to Central America is discussed.6) Line 133: The word "nodes" is missing.7) Line 141: Did the authors mean "iri8s" rather than "irits"?8) Is conjunc8vi8s an "immunological" complica8on?Reference #1 lists it simply as a "complica8on".9) Yersinia pseudotuberculosis was first described in 1883 but the first reported case was in 1911?Please clarify.Graphical abstract will illustrate the case study details more easily.It should elaborate case timeline and past medical history.5. Write methodology as a separate section and use subheadings to demonstrate each step.6.
Use subheading in the results section.7. Yersinia should be written only when mentioned for the first time in the manuscript then will bw written as Y. .8.
The whole paper needs a careful English grammar and spelling revision: 9.
References should be modified according to journal instructions: bold authors names, only first initial should be writtenand journal name should be italic.10.
Patient consent and ethical approval code should be provided.11.In Results section: antibiogram results should be clearly tabulated for both disc diffusion technique and E-test.12.In Discussion section: antibiogram susceptibility results should be compared with previously published articles.13.Was this patient suffering from SARS-CoV-2?. 14. Kindly add table of abbreviations (e.g.lines 95 and 96) and mention the normal ranges 15.Regarding bilirubin, direct, indirect and total values should be provided to determine type of jaundice.16.Line 106, add year of CLSI edition used.17.Adding antibiogram in material and methods section is recommended.18.
Antibiogram results for the isolate should be mentioned in details. 19.
Lines 117-122: this paragraph is not obvious at all and should be rewritten.

Reviewer 1 :
SatisfactoryTo what extent are the conclusions supported by the data?Reviewer 1: Partially support Do you have any concerns of possible image manipulation, plagiarism or any other unethical practices?Reviewer 1: No: If this manuscript involves human and/or animal work, have the subjects been treated in an ethical manner and the authors complied with the appropriate guidelines?Reviewer 1: Yes: Reviewer 1 Comments to Author: Dear author, 1-References 8, 13, 18, 19, 20, 21, 22, and 23 are old, please use new references.Reference 8 is the only description of Y. pseudotuberculosisoutbreak in a Canadian context, our patient's and institution's residence, and we believe this is an important reference to keep to provide local epidemiology of Y. pseudotuberculosis.Reference 13 has been replaced by a more recent reference.Reference 18 has been replaced by a more recent reference.Reference 19 has been replaced by a more recent reference.

2 -
Have you used positive and negative control?Please explain in the text of the article?Positive and negative controls were used as per CLSI guidelines for organism identification and susceptibility testing as part of the standard practice in the clinical laboratories.Kind regardsPlease rate the quality of the presentation and structure of the manuscript Reviewer 2: Very good To what extent are the conclusions supported by the data?Reviewer 2: Partially support Do you have any concerns of possible image manipulation, plagiarism or any other unethical practices?Reviewer 2: No: If this manuscript involves human and/or animal work, have the subjects been treated in an ethical manner and the authors complied with the appropriate guidelines?Reviewer 2: Yes: Reviewer 2 Comments to Author: 1. Description of the case(s): very good 2. Presentation of results: The presentation has details for the patient more than usual; for instance the vacancy time, family visit...I would recommend to only use the important information related to the clinical case including (signs and symptoms)

3 .
How the style and organization of the paper communicates and represents key findings: Good 4. Literature analysis or discussion Good 5. Any other relevant comments: Its good to add the image for the growth morphology of Yersinia to assist other researchers.

Reviewer 3 :
SatisfactoryTo what extent are the conclusions supported by the data?Reviewer 3: Partially support Do you have any concerns of possible image manipulation, plagiarism or any other unethical practices?Reviewer 3: No: If this manuscript involves human and/or animal work, have the subjects been treated in an ethical manner and the authors complied with the appropriate guidelines?Reviewer 3: No: i asked the author to provide ethical approval number Reviewer 3 Comments to Author: Reviewer comments: 1. Title: Suggestion: A case study of Yersinia pseudotuberculosis Bacteremia with Splenic Abscesses: A Case Report As our manuscript is a case report of a single patient without any study interventions, we have kept the title as "Yersinia pseudotuberculosis Bacteremia with Splenic Abscesses: A Case Report" 2. Author names: Kindly provide an Orchid ID.Rahel Tefera Zewude -ORCID -0000-0003-0044-7665 Aleksandra Stefanovic -ORCID -0000-0001-9299-2040 3. Keywords: I recommend addition of bacteremia to keywords and remove comma.

22 .
Regarding MALDI-TOF system: * Which Scores were considered reliable for species level identification?* Which scores were considered reliable for genus level identification?* Documented figure for MALDI-TOF data should be provided.* What are The Yersinia spp.included in the MALDI Biotyper?
d. Has the patient any previous hepatitis history?Patient has no prior hepatitis history.Many ThanksPlease rate the quality of the presentation and structure of the manuscript Reviewer 4: Poor To what extent are the conclusions supported by the data?Reviewer 4: Partially support Do you have any concerns of possible image manipulation, plagiarism or any other unethical practices?Reviewer 4: No: If this manuscript involves human and/or animal work, have the subjects been treated in an ethical manner and the authors complied with the appropriate guidelines?Reviewer 4: Yes:

10 )
figures to be two difference panels of the same figure instead.

Figure 1 1
Figure1and figure 2 are coronal and axial views of the same CT scan.However, given that different sections are presented with these different views, we believe that combining them into the same figure would misrepresent the sections and would not be optimal for clinician's assessment of these images.

10 )
Since the figure legends for Fig 1 and 2 are very similar, it is recommended for the two figures to be two difference panels of the same figure instead.Please rate the quality of the presentation and structure of the manuscript PoorTo what extent are the conclusions supported by the data?Partially supportDo you have any concerns of possible image manipulation, plagiarism or any other unethical practices?NoIs there a potential financial or other conflict of interest between yourself and the author(s)?NoIf this manuscript involves human and/or animal work, have the subjects been treated in an ethical manner and the authors complied with the appropriate guidelines?YesReviewer 2 recommendation and comments https://doi.org/10.1099/acmi.0.000525.v1.4 © 2023 Elshimy R.This is an open access peer review report distributed under the terms of the Creative Commons Attribution License.Rana Elshimy; ACU: Ahram Canadian University, microbiology and immunology, 19, Giza, EGYPT, 0223910142 https://orcid.org/0000-0002-5381-0037Date report received: 05 June 2023 Recommendation: Major Revision Comments: Reviewer comments: 1. Title: Suggestion: A case study of Yersinia pseudotuberculosis Bacteremia with Splenic Abscesses: A Case Report 2. Author names: Kindly provide an Orchid ID. 3. Keywords: I recommend addition of bacteremia to keywords and remove comma.4.

Table 1 .
Laboratory reference values

reasons to publish your next article with a Microbiology Society journal
Y. pseudotuberculosis infection represents an important differential diagnosis in patients with splenic abscesses.Exposure to contaminated water, vegetables and dairy products should be assessed in such cases to determine modes of acquisition of Y. pseudotuberculosis infection.Immunosuppression and iron overload disorders such as haemochromatosis and chronic liver disease are important risk factors for severe and disseminated Y. pseudotuberculosis infections where it carries a high fatality rate in these patient populations.Manifestations of Y. pseudotuberculosis can range from mild gastroenteritis to sepsis and abscesses in the spleen, liver and lung.In addition to treating yersiniosis with antimicrobials, it is also important to monitor patients for immunological complications such as erythema nodosum, glomerulonephritis, conjunctivitis and Kawasaki disease.26.Rathmell WK, Arguin P, Chan S, Yu A. Yersinia pseudotuberculosis bacteremia and splenic abscess in a patient with non-insulindependent diabetes mellitus.West J Med 1999;170:110-112.27.Van Zonneveld M, Droogh JM, Fieren M, Gyssens IC, Van Gelder T, et al.Yersinia pseudotuberculosis bacteraemia in a kidney transplant patient.Nephrol Dial Transplant 2002;17:2252-2254.Author feedback says our Editors are 'thorough and fair' and 'patient and caring'. 5. Increase your reach and impact and share your research more widely.
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20. Discussion is too long 21.Line 170: bacterial names should be italics 22. Regarding MALDI-TOF system: * Which Scores were considered reliable for species level identification?* Which scores were considered reliable for genus level identification?* Documented figure for MALDI-TOF data should be provided.* What are The Yersinia spp.included in the MALDI Biotyper?23.
conclusion must be rewritten and supported by data 24.Lines 157-160: